Becoming Pack
by wolfsrainrules
Summary: It's the end of everything. Everything they knew is gone, and all they have is each other. If they want to survive they'll need to lean on each other and by the end of it their bonds will have never been stronger. (Zombie AU. Fem!27 Teen!Reborn. Fem27/Reborn)
1. Chapter 1

**I was on K. D. Ownz profile, and I misread the sentences "I like R27. Wouldn't it be awesome to fight in a Zombie Apocalypse?" I read it as "I like R27, wouldn't it be awesome to see them in a Zombie Apocalypse" and thus….this was born.**

**I don't own KHR or the L4D zombies I am borrowing (though I am changing one or two things about them). This applies throughout.  
>Warnings: OOC! AU! Fem!27 Teen!Reborn. RFem! 27!  
><strong>O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~

Natsume ran.

She didn't have enough time.

_She didn't have enough time._

She ran faster. She didn't even understand _why_ she was running, she just _knew_ she needed to gather her friends and get out of Namimori. She already had Yamamoto, Gokudera, Lambo, I-Pin, Fuuta and Bianchi waiting at the borders. She needed to get Ryohei, Kyoko, Haru, Shamal, Shoichi, Spanner, Hibari, Chrome, Mukuro Ken, and Chikusa.

_She didn't have enough time._

Natsume cursed in her head. Her Hyper Intuition was _screaming_ at her in a way it had never done before. She took a moment to be silently thankful that Mama was out of the country visiting her father and therefore was safe.

She muttered another curse and reached for the cell phone Reborn had insisted she keep on her person. She held the two down without pausing speed dialing Reborn. She was one of a handful of people who had a direct line to Reborn and she knew it. "Dame-"

Natsume didn't let him continue, interrupting him in a way she normally wouldn't contemplate even in her dreams, and snapped out "Reborn."

The tone in her voice had Reborn straightening instinctively recognizing it as the tone of a Boss and instinctively responding to the 17 year old woman he had chosen to follow. "Natsume?" his voice was all business as he answered her.

"Gather everyone. I don't care how you do it. I need _everyone_ together and out of Namimori thirty minutes ago. We _cannot_ be in the city in twenty minutes do you hear me? _**Get them out.**_"

Reborn was running to obey the commands before he even registered his own movements. "Status?" he barked the question.

Natsume shook her head. "Something…I don't know what it is Reborn but my Intuition is screaming so loudly it actually _hurts_. We need to be out of Namimori in twenty minutes at the latest or we are going to be in serious trouble. I have Yamamoto, Gokudera, Lambo, I-Pin, Fuuta and Bianchi waiting at the borders but everyone else it still in town. Please. Reborn get them out."

Reborn _did not_ like the pleading tone in his student's voice.

As if she needed to plead for him to follow her especially in this state. The girl had no idea what she had done to him without even trying. He'd storm Hell's Gates at her side and not even bat an eye. (Not that he'd _tell_ her that mind.) "I'll get them Natsume."

"Twenty Minutes Reborn."

"Understood." His Boss had given him a command and a plea wrapped into one and Reborn had yet to fail at anything he did. He didn't plan to start now, especially since it had been Natsume to ask. He started making calls and directing people to the borders of Namimori closest to Natsume's house. Shamal, Shoichi and Spanner where easily directed out of the town.

Natsume sagged in relief even as she continued to run. With Reborn's help she just might have enough time. She dialed Mukuro next. "Young Vongola~ What do I owe the pleasure?"

"Mukuro," on the other end of the phone Mukuro tensed and straightened at her tone "Mukuro you need to take Chrome and the others and _get out_. Get out of the town. I don't know what's coming, but I know we need to get out, we cannot be here. We need to be gone in the next twenty minutes or we're going to be in serious trouble."

Mukuro had followed and given his loyalty to _one_ person in his life and that person was Natsume Sawada. Natsume who had earned every scrap of his loyalty and regard one slow staggering step at a time. Mukuro may play with Natsume still, but she was his Sky who had fought to allow her Mist to roam freely under her light and Mukuro had learned to read the girl. He _knew_ she meant what she was saying, could sense that he needed to obey this command, that this was different than any other command she had given. "I will go Natsume. Chrome, Chikusa, and Ken and with me, but M.M. is in Italy. I will take them with me."

"Thank you Mukuro. Hurry. We only have a little less than twenty minutes to get out of town."

She hung up without pause. Reborn would deal with Hibari, but she needed to get Ryohei, Kyoko and Haru out. She moved for the Cake shop first and found Kyoko and Haru sitting there together. "Kyoko!"

The girl turned at the sound of her name, her eyes widening with surprise as she focused on a very windblown, very upset Natsume. "Mei-chan?! Are you okay? What's wrong?" she stood and took a step forward towards Natsume.

"Kyoko, where's your brother?"

"Down the street Mei-chan. Why-?"

"I'm sorry Kyoko-chan, but I don't have time to explain. I need to get your brother and then we need to go. We're on a very strict time limit and I promise to tell you what I can afterwards but right now I need you to trust me. You too Haru."

The two girls closed their mouths and nodded slowly after looking at Natsume. Natsume was usually composed nowadays (as opposed to her younger chaotic years- after a while you learn to roll with the punches especially when Reborn is the one throwing the punch) and to see her looking so hassled and worried and anxious let them know that now was not the time to argue with her or ask questions.

Natsume nodded once and spun on her heel before running out the store and straight for her Sun Guardian.

After a short conversation with Ryohei she was back to the cake shop which Kyoko and Haru stood outside of. Without pause Natsume grabbed Haru and swung her up onto her back (Silently thanking Reborn for the hellish training he had put her through for the past few years) and ran for the rest of her group. Ryohei didn't pause as he swung his sister onto his back and followed after his little sister figure and boss.

O~O~O~O~

By the time Natsume arrived outside the town where her friends and chosen family were waiting for her she was staggering every couple of feet. She wasn't out of breath or anything- wasn't even tired- the reason she was staggering every few feet was due to her Hyper Intuition.

It _**hurt**_.

It was throbbing and stabbing at her and she wanted to scream, but she couldn't stop despite the pain. She only had ten minutes to get the others out of the town and underground.

She staggered up to the others, instantly putting them all on guard and causing them to worry. She commanded them. "Reborn. Lead the way. We need to be underground in the next ten minutes. Do not argue with me. Just _move._" Her hand flew to her head and clenched in toffee-caramel hair as her head throbbed again and she sucked in a sharp breath her vision sharpening as her Intuition forced her into a partial transformation of her Hyper Dying Will Mode. When she opened her eyes and bright swirling orange met the eyes of everyone around her no one argued. They turned to Reborn who nodded once and turned breaking out into a run silently thankful for his 18 year old self's long legs rather than his 2 year old self.

They made it with two minutes to spare. (Reborn didn't even wonder how Natsume had known about the underground base he had made a month before- he knew her Intuition had to have told her especially since it had been so powerful about it.)

Two minutes and five seconds after the group had made it underground Natsume staggered sideways as if she had been hit around the head with a bat and cried out her hands flying to her head.

She dropped like a stone.

Hibari had been closest and he snagged her before she hit the ground. He may have been annoyed about being bothered, but the moment he had seen the Omnivore he had known it was serious and bit back the demand for answers. Natsume Sawada had earned his regard. He had watched her grow from a pathetic herbivore to a carnivore with a soft heart- hence the label of omnivore. She had earned his respect, had offered him a place to call home without chaining him, had offered him stronger and stronger opponents to fight and he would not allow anyone to harm her while he drew breath. He held her upper body up with one hand grey eyes focused on her face as her eyes opened a sliver and Hibari drew in a sharp breath.

Her eyes were lit up like the sun brighter and more vivid then he had ever seen with her flame. He carefully lowered her down as the bomb-herbivore panicked while laying his jacket under their Sky's head.

Reborn's hands were glowing yellow as he reached for her next carefully searching for what could have hurt her.

Nothing was showing up even as Natsume arched off the floor and cried out again. Her eyes opened blindly and all the others- having gathered around her when Hibari moved to the door they entered through- all got to see what Hibari had glimpsed.

Natsume's eyes were lit up so brightly her face was actually covered in an orange glow. It was as if the room was pitch-black and someone had lit a fire inside her eyes they were so bright. Not one person breathed until she closed them again.

"Reborn? What is that? I've never heard of any Sky's eyes glowing that brightly."

Reborn stared down at his student. "I…don't know. I've never seen or heard of it either." He bent and carefully lifted her off the floor into his arms. "Come on. This is just the entrance room. There are tunnels that will lead to a large base we can use until Natsume is alright." Reborn lead the others forward through the tunnels and into the much larger base without a word placing Natsume down into a makeshift Infirmary that was already stocked with all the supplies Reborn could get into it in a month.

Shamal moved forward without prompting to see if he had better luck finding what had happened to Natsume as a Doctor.

He didn't.

They would have to wait for her to wake on her own.

O~O~O~

Natsume shot up with a gasp.

It had been horrible.

She had _felt it._

She had _felt_ as the lives of almost everyone above their hiding place snuffed out, as their bodies shifted and mutated and changed in death, as some mutated even more into walking _nightmares_ and it had _hurt_. It had hurt to feel them all disappear and leave behind the twisted nightmares in their place that felt so very wrong. She moaned in horror.

Nothing would ever be the same again.

Not after this.

She couldn't feel them anymore, not like she had when their lives had been snuffed out but before the connection had broken she had felt maybe three or five survivors. She could sense the mess of…of _things_ above their hiding place and she shuddered. They were in _so much trouble_.

She drew in another sharp breath as a thought registered in her mind. Something she had known subconsciously as she gathered her chosen family together to hide them from what was coming but hadn't _realized_ until her Intuition had shoved it into the front of her mind that very moment.

They would not be able to leave the underground until they knew how to survive _together_.

She refused, _**she refused**_, to allow _**any**_ of them to die before she had stopped breathing herself and even if she had to take drastic measures _no one_ was leaving until they would and could work together to survive. She could sense it. Going outside as they were now was akin to suicide and she wouldn't lose anyone.

She lifted her head from where she had been cradling it. She was inside a makeshift Infirmary. Most of her Guardians were in various states of sleep around her. Kyoko had curled up with the children and Haru, while Bianchi was leaning against the wall near Gokudera. Mukuro and Hibari were missing along with Shoichi, Spanner, and Mukuro's group. Shamal was opening the door to the Infirmary and paused when he saw her watching him before moving forward and quickly checking her over. Reborn came in a few minutes after Shamal and upon seeing her awake he glided forward to the chair next to her bed and commanded "Explain."

Natsume grimaced. "I felt them all." She paused, reliving the moment she had felt so many people's life-forces flicker out like candles in the wind "They all died and I _felt it_ and it _hurt._"

The two men straightened up. "Felt who die?"

Natsume turned her eyes to Reborn again "I felt the entire town. There's no one there anymore Reborn. They all died and they left their _shells_ behind as twisted _things_. There are maybe three people left alive inside Namimori."

"_What?_"

Natsume's eyes darted to Shamal as he whispered the question. Natsume shook her head "I don't know what caused it, or how it actually happened, but _something_ swept over the town and right now we are basically all that's left of Namimori. Everything out there is a mutated corpse. And whatever they are now they're dangerous. We can't leave here. Not until everyone can work together or we'll die. We're going to _need_ each other or we won't make it out alive." She pulled sharply on her hair. "It's going to be the survival of the fittest out there and the _only_ thing we are going to have out there is each other. It's war and death and destruction." She turned sharp eyes to Reborn. "You're going to have to whip _everyone_ into shape. I know you can do it and we are going to need it."

Reborn stilled under her eyes, seeing the truth and resolve in them.

She meant what she was saying.

Outside was a warzone.

She needed him to whip the others into shape or they'd all die.

His eyes narrowed sharply.

He had not helped Natsume gather her Family together, had not watched them all bleed and fight together, had not watched as bonds formed and grew between them all so that they could all die.

He nodded at her, lifting his hat off his head and over his heart. "As you wish Decimo."

He would whip them all into shape for war.


	2. Chapter 2

The first week was hell for everyone.

Everyone had basically lived on their own or with smaller groups inside their homes with the option of leaving for a while always there. It was an exercise in and of itself to become accustomed to having 19 people in one space- especially when two of said people were Mukuro and Hibari- much less trying to do so while confined to a small space with the option of escape being unavailable.

Fights broke out constantly and the only thing that stopped the underground base from collapsing around them was the fact that Reborn had had it reinforced with Flames while it was being built making everything inside the base much more durable than it otherwise would have been. (Not that there weren't damages in a few places, but it was holding remarkably well considering.)

Tempers were short, people were fighting, sleep was hard to come by, privacy near impossible and everyone had been evaluated by Reborn in preparation for their training. Habits, strengths, weaknesses…everything Reborn thought he would need to train them all was pried from everyone- even the most stubborn.

What eventually caused everyone to settle down a bit was the first of a long list of close calls.

Haru and Kyoko, while they had been aware of what it was their friends and brother had been involved in for the last few years, had not in any way been prepared to be shoved into close quarters with them and all the chaos that came from their close proximity.

They had been unable to deal with it and had left the protection of the base.

Natsume had realized what happened only a few minutes later and upon realizing that everyone was fighting again and that she didn't have the time to try and stop them so they could help her Natsume had simply stopped long enough to grab two katana for the girls and put her gloves on before she was out the door and following after the girls as quickly and quietly as she could manage.

She found them due to the noise. The girls were running and Natsume could see at least 25 of the more common _things_ attacking them. The girls were fighting back where they could, but were mostly running. Natsume didn't hesitate. She lunged forward, the noise drawling the attention of the outermost horde, pulling one of the katana free from her back. She swung it hard slicing the first few things that lunged at her in half without pause. She continued her lunge quickly slashing at anything that got in her way as she quickly managed to get to the girls' side. "Kyoko! Haru!"

"Mei-chan!"

"Here!" Natsume slashed through another zombie before she handed the katana over to Kyoko. Kyoko took the sword thankfully spinning on her heel to lash out at the creatures that had approached her. Natsume quickly handed the other katana off to Haru before lighting her gloves.

The three girls fought viciously.

Kyoko didn't look like it, but one could not be Ryohei Sasagawa's little sister without being taught some kind of fighting ability. She didn't like fighting, didn't want her brother to go out _looking_ for a fight or starting one but she had nothing against _defending_ yourself or others. That protective instinct her brother had ran in the family. She knew the basics of using a sword, could use it without hurting herself. It was actually _this_ ability that had first drawn her to the attention of Kensuke Mochida rather than her status of School Idol.

Haru also knew how to handle the sword without harming herself, though she had learned for her Cosplay Club. She silently thanked whoever was listening as she sliced though anything that moved that wasn't Mei-chan or Kyoko-chan.

Natsume cursed firing another condensed fireball at the closest creature. (She didn't curse very often, but Natsume thought the situation called for it.) They still had another eleven creatures to deal with and she _knew_ the noise they were making would draw more and more creatures to their side.

Maybe even one of those twisted creatures. The ones that had twisted into something different than most of the others. The walking nightmares. (She felt sick at the idea.)

Her eyes widened as the creatures seemed to shift and lunged all together in a horde. She heard Haru shriek and turned her head quickly. Haru had five of the creatures lunging at her from all directions and was having problems with so many. Natsume cursed again even as she fired a small controlled steam of her flame through the creatures in front of Haru, freeing Haru up to deal with the two coming from the back.

Eight more.

Natsume turned blinking in surprise as Kyoko's katana flashed by her face beheading a creature that had lunged for her while she had helped Haru. "Thanks Kyoko-chan."

"No problem."

Seven.

Natsume lunged into the fight again using quick face grabs to set any creature that approached on fire and into ash. She dealt with two quickly even as Haru dealt with one of the two attacking her.

Four left.

Kyoko spun sharply, the blade flashing again, and sliced cleanly through another. Natsume used a few fireballs to kill another.

Two left.

Kyoko and Haru dealt with the last two creatures and Natsume thought they would make it back without any serious trouble.

Then she heard the sobbing.

Her Hyper Intuition spiked sharply even as Haru and Kyoko turned and called out "Hello? Are you alright?"

"No!"

But it was too late.

Natsume lunged forward knocking Kyoko and Haru to the side even as the pale grey-white skinned girl with long talon-like appendages in place of fingers came barreling out of the trees and straight at her side. Natsume didn't quite have the time to brace for it or block the girl as the talons came up and sliced at her.

She cried out as the talons bit through her flesh hearing Kyoko and Haru cry her name even as she hit the floor and rolled. She brought her mittens up, relighting them into her glove state ignoring the injury to block the girl who was turning and barreling her way again.

Natsume managed to block the next attack, flinching as the laceration in her side pulled at the movement and resulting pressure. She could see Haru and Kyoko lunging forward to help her even as she was forced to release the girl after delivering a strong punch to her head.

The girl staggered sideways before lunging her way again. Kyoko and Haru managed to injure her even as Natsume braced for another attack trying to ignore how damp her shirt and pants felt. The girl lunged, talons first, for Natsume's head. Natsume quickly dodged, earning a few scratches on her cheek in the process even as she spun delivering a flaming backhand to the girl's face. Haru took advantage of the girl's dazed state lunging forward and decapitating the girl.

Natsume staggered after a breathless moment, her gloves fading back into mittens, as they all waited to see if anymore creatures would lunge out of the woodwork. Her wound was deep and as adrenaline faded blood loss made itself known.

Haru and Kyoko quickly lunged to her side supporting her weight and helping her back towards the base while Natsume managed a quiet warning "Be quiet. Noise draws their attention."

They all staggered back inside the base waiting only long enough for the entrance to shut before Kyoko and Haru were screaming for Shamal even as they continued to drag a flagging Natsume towards the Infirmary.

Natsume remembers the clatter of noise as everyone rushed for the Infirmary at the sound of Haru and Kyoko's panic, she remembers being laid down, remembers the door slamming open and the ringing silence so filled with tension she could feel it even in her semiconscious state, remembers Shamal and Reborn rushing forward to help her, remembers steady hands on her face, a warm voice and gentle fingers.

O~O~O~

It took Natsume stumbling back coated in red from her ribs to her thighs with Haru and Kyoko on either side of her, both pale and shaking with tears running down their faces and various scratches and bruises on them both for the constant chaos of the base to settle down. It was jarring for all of them to see Kyoko and Haru who never participated in any of the violence stagger into the base obviously having been fighting especially considering they were supporting Natsume between them, dripping blood from her shirt.

When it was explained that the only reason Natsume was hurt at all was because she went after Kyoko and Haru when the two girls left the base for a break from all the fighting, that Natsume didn't stop to ask for help because it would take too long to stop their fighting, that Haru and Kyoko would- in all likelihood- have died if Natsume hadn't come after them with weapons and then put herself between the enemy and the girls….well it was like a slap to the face.

Reborn took one look at the long vicious claw marks running from just under Natsume's ribs from her front left, around her side and down to her left hip on her back and decided he was going to _beat_ teamwork into the heads of his charges.

He would _**never**_ see Natsume injured like this due to infighting ever again.

~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~O~

**Okay. This is short, but next chapter is going to have quick looks at the training, followed by a time skip, and then scattered throughout the other chapters will be flashbacks to more in depth looks at training.**


End file.
